numerous: Tipperary, Kilkenny, Wexford etc. Ir. Ó Dubhuidhir (Duibhir). The derivation is from dubh + Odhar, a first name meaning dun-coloured. A name famous for their part in the Resistance, they usually appear as O'Dwyer. IF,MIF & SGG.

O'Dwyer:

Very numerous: all areas, especially Munster and South East. Ir. Ó Duibhir (dubh + odhar, dark brown). A sept of Tipperary, immortalised in the song "Seán Ó Duibhir a' Ghleanna".IF.